Weight-bearing exercise and markers of bone turnover in female athletes.
Weight-bearing activity provides an osteogenic stimulus, while effects of swimming on bone are unclear. We evaluated bone mineral density (BMD) and markers of bone turnover in female athletes (n = 41, age 20.7 yr) comparing three impact groups, high impact (High, basketball and volleyball, n = 14), medium impact (Med, soccer and track, n = 13), and nonimpact (Non, swimming, n = 7), with sedentary age-matched controls (Con, n = 7). BMD was assessed by dual-energy X-ray absorptiometry at the lumbar spine, femoral neck (FN), Ward’s triangle, and trochanter (TR); bone resorption estimated from urinary cross-linked N-telopeptides (NTx); and bone formation determined from serum osteocalcin. Adjusted BMD (g/cm; covariates: body mass index, weight, and calcium and calorie intake) was greater at the FN and TR in the High group (1.27 +/- 0.03 and 1.05 +/- 0.03) than in the
Non (1.05 +/- 0.04 and 0.86 +/- 0.04) and
Con (1.03 +/- 0.05 and 0.85 +/- 0.05) groups and greater at the TR in the
Med group (1.01 +/- 0.03) than in the
Non (0.86 +/- 0.04) and
Con (0.85 +/- 0.05) groups. Total body BMD was higher in the
High group (4.9 +/- 0.12) than in the
Med (4.5 +/- 0.12),
Non (4.2 +/- 0.14), and
Con (4.1 +/- 0.17) groups and greater in the Med group than in the Non and Con groups. Bone formation was lower in the
Non group (19.8 +/- 2.6) than in the
High (30.6 +/- 3.0) and
Med (32.9 +/- 1.9, P < or = 0.05) groups. No differences in a marker of bone resorption (NTx) were noted. This indicates that women who participate in impact sports such as volleyball and basketball had higher BMDs and bone formation values than female swimmers.